Bad Error Messages Waste Time
The only thing worse than content-free error messages such as "Error 0" (see The $4,000 Error Message) are those that mislead: telling you that X is wrong when it’s really Y that’s the cause of the problem. At least with "Error 0", you’ll look at everything and think about all of the possible things that could be wrong and either see your mistake or give up and try something completely different.
The evil misleading error message, however, causes you to spend your time and effort on fixing X, until you finally realize (after much cursing and coffee drinking) that there’s no problem with X, X is just fine and works exactly as expected. Only then do you see that Y is the real problem and, even worse, it takes only two seconds to fix it.
This is why programmers should never write error messages. Just like they should never write help text, button labels, menu items, or pretty much any text that the end-user is going to read. That’s the job of the usability/documentation folks: they know how to write. This is also why QA should pay close attention to the error messages (they are testing the error cases, right?) and ensure that they are correct.
Of course, the best solution is to prevent the error conditions in the first place, but that’s another rant.
